Over-voltage protective device



L.S.BRAQH JuEy W353.

OVER-VOLTAGE PROTECTIVE DEVICE Filed Jan. 7, 1935 Z $heets-Sheet l IMVENTOR Z ewz 57 @9522 ATTORNEY L. s. ERAQH 249,364

OVER-VOLTAGE PROTECTIVE DEVICE Filed Jan. 7, 1955 3 Sheets-$heet 2 iNVENTOR 27652? i Z3 40??? ATTORNEY L. s. BRACH 9 OVER-VOLTAGE PROTECTIVE DEVICE Filed Jan. 7, 1935 5 Sheets-Sheet 3 INVENTOR ZFQQ 5 x ATTORN E! Patented July 19, 1938 ,UNITED STATES PATENT OFFICE 2,124,364 OVER-VOLTAGE PROTECTIVE DEVICE Leon S. Brach, East Orange, N. J.

Application January '1, 1935, Serial No. 708

12 Claims. (01. 175-215) This invention relates to improvements in arresters especially adapted for low voltage service. Generally speaking, lightning arresters are primarily intended as protecting devices against a lightning discharge or an impulse resulting from such discharge. However, the term lightning arrester? is also understood to include a protective device used to protect against an abnormal over-voltage current coming from another'circuit. Such over-voltage may result from a surge induced from paralleling high-tension lines with a closely adjacent low voltage circuit, or a cross between the high-tension line and the low voltage line, thereby subjecting the arrester to a high voltage and heavycurrent. A

Having heretofore designed lightning arresters using enclosed gaps, the enclosure being filled with some rare gas such' as neon, and having observed the action of such arresters, and further having studied and observed the action of thermostatic bi-metallic strips in various arrangements, I have conceived the idea of combining a rare-gas-iilled tube with thermostatic or bi-metallic strips to form gaps within such tubes, as

well as exterior thereof, into an improved form of arrester.

In the manufacture of arresters of the vacuum or rare-gas type, using bi-metallic electrodes, whether the electrodes are supported by the leadin wires or on a special electrode support, it is difficult, because of the large amount of heat generated between the electrodes on the passage of current therebetween, to secure a fixed dimension of the gap between two or more electrodes,

and even though the gap may be originally established at a fixed distance, when current passes between the electrodes or a discharge takes place,

the bi-metallic electrodes press against eachdistance between the initial arcing portions of the electrodes to a given predetermined value, and it is therefore one of the objects of my present invention to provide ways and means for.

55 preventing the contact-engaging parts of the electrodes, or those portions of the electrodes between which the high voltage current passes, from separating beyond a predetermined distance after the discharge is passed and the source of over-voltage current removed, whereby the 5 arrester electrodes may return to their normal position.

Another object of my invention is to provide an arrangement of electrodes so that the arc will be quenched in the shortest possible time. 10

Another object of my invention is to provide a protective device of the class to be described in which means are provided for insuring that the over-voltage current will jump between the electrodes within certain limits or areas. 15

Another object of my invention is to provide means for relieving, after a certain interval, the electrodes within the sealed chamber from the full discharge current that passes between the electrodes within the said chamber, or in other words, to provide means for preventing the tube or sealed-in chamber from being injured or destroyed from the over-voltage current if this continues to pass through the arrester for any great length of time. 25

Another object of my invention is to combine within a rare-gas tube, or immediately associated with it externally, features that will be responsive to abnormal current, so that this abnormal current will be either grounded or open-circuited, 30 thereby having the arrester unit combine both protection for over-voltage and/or current.

A still further object of my invention is to provide physical protection from mechanical injury or from the elements to the auxiliary gap 3r portions of an arrester and at thesame time have these parts readily visible for inspection.

These and other objects will be clear to one skilled in this particular art after a reading of the specification taken in connection with the 40 annexed drawings, which are more or less diagrammatic in form to better illustrate the application of the principles involved. In the drawmgs:

, Figure 1 is a part-sectional and part-elevationa1 view through one form of my over-voltage protective device, showing one pair of electrodes mounted within a sealed tube or chamber, the lead-in wires to the electrodes being at one end of the tubes.

Figure 2 is a view similar to Figure 1 but showing the lead-in wires coming out at opposite ends of the tubes.

Figure 3 is a modified form of the device shown in Figure 2.

Figure 4 is a view similar to Figure l, but showing an, additional means for preventing the overvoltage current from jumping between the leadin ends of the electrodes.

Figure 5 is a view similar to Figure 1, but showing additional or supplemental members for assisting in carrying the over-voltage current.

Figure 6 is a view similar to Figure 5, but showing a modified form of electrode.

Figure '7 is a-view on the line l--! of Figure 6 with the parts turned ninety degrees.

Figure 8 is a modified form of the device shown in Figure 1.

Figure 9 is a modified form of the device shown in Figure 4.

Figure 10 shows a further modified form of my arrester in which parts exterior to the sealed chamber are used to protect the tube or chamber from being injured or destroyed on continued passage of the over-voltage current.

Figure 11 is a modification of the form shown in Figure 10.

Figure 12 shows a still further modified form of the structure shown in Figure 10.

Figure 13 is a still further modification of the form shown in Figure 10.

Figure 14 shows a still further modification of one form of my protective device.

Figure 15shows a modification of the device shown in Figure 14.

Figure 16 is a partial view of the bottom portion of my new form of arrester, showing the manner of connecting the lead-in wires to the electrodes.

Figure 17 is a view of an arrester having electrodes similar to those shown in Figure 9, but in which an additional element is introduced to take care of sneak current.

Figure 18 is a modified form of the arrester shown in Figure 17.

Figure 19 is a slightly modified form of the arrester shown in Figure 13.

Figure 20 shows a modified form of a combination of the arrester shown in Figures 17 and 19;.

Figure 21 shows a further modified form of the arrester.

In, the various views, wherein like numbers voltage current therebetween. These contacts.

may be of carbon to avoid fusing of the metal on passage of the current between the electrodes. When carbon contacts are used, I prefer to fasten these contacts to the metal of the electrodes 2 and 3 by spraying one side of the carbon contacts with a heavy layer of copper and then welding the copper to the electrode. Some other satisfactory way of applying the copper to the carbonmay be used.

In other words, when the over-voltage current comes. into the arrester on one of the lead-in wires and jumps from one of the contacts-say from 6 to i-an arc is started which generates a relatively large amount of heat in a very short space of time, and this heat acts on the bimenace metallic thermostat strips 2 and t, causing them to bend so as to bring the contacts 5 and i into engagement, thereby cutting out the arc. The exterior apparatus associated with the arrester to indicate the presence of such over-voltage curr t on the device is not shown as this forms no part of my invention, but it will be understood that this additional apparatus gives an indication of the presence of such over-voltage current so the attendant in charge may look into and remove the troublesome current.

After the electrodes 2 and 3 have cooled suificiently, the electrodes separate, and to insure that this separation will come back to its normal initial value, I have provided means to bring about this desirable condition. I I accomplish this by bending over the end 9 of the electrode 2 and the end 9 of the electrode 8, so that they engage the inner wall of the tube or chamber 8, whichchamber is preferably evacuated, and filled with an inert gas such as neon.

In Figure 2, the electrodes 2 and 3 are mounted within the chamber so that the lead-in wires come into the tube from opposite ends, otherwise the action is the same as of the device shown in Figure 1.

In Figure 3, the electrode 2 carries a-member Id which may be an insulator, and this in turn carrier an insulator ii, preferably of mica, which overhangs at l2 the end of the electrode 3, thus acting to normally position the contacts 5 and i at a given predetermined distance apart.

In Figure 4, the electrode 2 is provided with an insulating sleeve l3, preferably of glass, so as to prevent the over-voltage current from passing between the electrodes 2 and 3 at any point near the lead-in wires d and 5. This construc- '.tion is such as to force the over-voltage current to always jump between the contacts 6 and i.

. This additional protective means may be used on all of the forms of arresters shown herein.

In Figure 5, the electrodes 2 and 3 have associated therewithauxiliary bi-metallic members M and i5 which-are fastened to the electrodes 2 and 3 adjacent the point where the lead-in wires 4 and 5 come into the chamber.

When the over-voltage current passes between the contacts 6 and l and continues for a considerable interval of time, the heat generated causes the-auxiliary bi-metallic elements it and i5 to operate so that their free ends come into engagement with the electrodes 2 and 3 at points adjacent the contacts 6 and l, thereby reenforcing the current-carrying capacity of the electrodes 2 and 3, so that the danger of permanently injuring the electrodes 2 and 3 by the heavy over-voltage current is thereby lessened.

In Figure 6, the electrode 2 is divided into two arms l6 and ii, while the electrode 3 is divided into two arms l8 and is. Each of the arms it to l9 inclusive carries contacts or contact-engaging portions, and in some cases I prefer to make the gap 20 between the arms ill and is less than the'gap 2| between the arms 56 and it, so that the over-voltage current will jump between the shorter gap, and then if the current continues at an abnormal interval, the gap 28 will close to divide the current between the respective sets oi arms.

In Figure 8, a metal plate 22 is shown as being fastened within the chamber between the contacts 6 and l and connected to a lead-in wire 23. Thus the over-voltage current may function between the electrode 2 and the ground plate 22 independent of the electrode 3, or the electrode 3 may function with the ground plate 22 independent of the electrode 2.

In Figure 9, the electrodes 2 and 3 have formations 24 and 25 providing predetermined portions thereof for the passage of the over-voltage current therebetween. As in Figure 7, the gap 23 is preferably made smaller than the gap 2|, so the initial discharge of the over-voltage current takes place between the gap 20, and if this continues for a length of time after the portions come into engagement, then the gap 2| will be closed, bringing into engagement the contact portions 25. This construction, causing the current to jump at a predetermined point on the bi-metallic strip, will cause it to flex more quickly.

In Figure 10, the tube or container I is positioned within a shell 26 of insulating material having metallic terminals or thimbles 21 and 28 which may be used for mounting the arrester between suitable spring clips. The lead-in wire 4 is connected to the thimble 28 and the lead-in wire 5 is connected to the thimble 21. In this form' of protective device, the contact surface portions 24 of Figure 9 are replaced by contacts 29 and 30 to form the gap 20, while the surfaces 25 of Figure 9 are replaced by contacts 3i and 32 to form the gap 2I. Exterior of the tube or container I, are a pair of bi-metallic strips 33 and 34, one end of each being mounted to the thimble 28, while their free ends 35 are adapted to engage the interior surface of the thimble 21 when the bi-metallic elements 33 and 34 operate under the influence of the heat delivered from the tube I by reason of a prolonged passage of over-voltage current therethrough. As soon as the thermostat elements 33 and 34 contact with the thimble 21, the greater part of the current is shunted away from the tube portion of the arrester, it being understood that the strips 33 and 34 are considerably larger in current-carrying capacity than the electrodes 2 and 3.

In Figure 11, the tube construction is in general the same as in Figure 10, but the exterior automatic safetymeans is different. This automatic means consists of a plurality of bi-metallic strips 36, 31 and 38 which may be arranged in one or more groups around the periphery of the cessfully adding shunting elements around the tube portion of the arrester.

In Figure 12, the thermostat electrodes are shaped similar to those shown in Figure 9, but arranged in a manner similar to that in Figure 11, the entire tube structure being mounted, however, within a special casing 42 of glass which carries terminals 43 and 44 for making connection to the arrester. The housing 42 being made of glass, an observer can readily see the functioning of the parts within the tube I. As a safety device around the tube I, I provide bi-metallic strips 45 and 4B which act to shunt the tube arrester I in a manner somewhat similar to that described in Figure 10.

In Figure 13, the tube I has electrodes which are a combination of those shown in Figures 9 and 10. It also has protective thermostat elements the same as 33 and 34 of Figure 10, but in this case, the ends 41 and 43 are adapted to be brought into engagement by abnormal generation of heat by the tube I, thereby shunting the current around the tube portion of the arrester. In this form of construction, the shell 43, made oi any suitable material, preferably glass, may be fastened to a base 53 of insulating material as by means of snap springs 5|. The base carries terminals 52 and 53 for mounting the arrester in a suitable socket.

While the auxiliary electrodes 41 and 48 are enclosed within the shell or casing 49, it may be noted that the auxiliary electrodes 45 and 46 in Figure 12 are also fully enclosed within the easing 42 by means of suitable insulating strips 60 which may be held in place by any satisfactory means as cement 6|. 1

In Figure 14, a single bi-metallic electrode 54 is sealed within a metallic chamber 55 which is supported by a glass sealing means 56. Within one end of the container 55 is positioned an insulator 51 preferably of porcelain which acts as a stop and positioning means for the free end of the electrode 54. The electrode 54 carries a contact 53 adapted to engage the metallic shell 55 on action of the bi-metallic thermostat 54 due to the passage of current from the contact 53 to the shell 55.

In Figure 15, the end of the metallic shell 55 may be sealed into a glass insulator 59 which also has a part acting as stop and positioning means for the free end of the electrode 54. The insulator 59 being made of glass, this acts as a window whereby the action of the thermostat element within the container 55 may be observed.

In Figure 16, the electrode ends 2 and 3 are formed away from each other and are connected to the lead-in wires 4 and 5 in a manner somewhat as shown. If desired, the electrodes 2 and 3 may rest on the insulating bosses 62 where the lead-in wires are brought through into the tube I. This construction acts to prevent abnormal voltage from jumping from one electrode to the other at the points where the lead-in wires come into the tube. In other words, the construction is a preventive means which may be used in place of the insulating member I3 shown in Figure 9. It may be noted at this point that the ends of the electrodes 2 and 3, where they are joined to the lead-in wires, including the ends of the lead-in wires, may be covered with an insulating paint or varnish to prevent over-voltage from jumping across the electrodes at these points.

In Figure 17, one of the electrodes, for example 3, maybe-provided with a heating device in the form of a resistance coil 63, one end of which is connected to the electrode 3 at some point adjacent the place where the lead-in wire is connected to said electrode, while the other end of the coil 53 is carried out to a terminal 64. While the heater is shown as a coil 63, this may take some other form. In this arrangement, the leadin wire 64 may be considered as the incoming line circuit, while the lead-in wire 5 may be considered as going to the instrument with which the arrester is associated. The other electrode connected to the lead-in wire 4 is connected to ground. Thus any current coming in over the lead-in wire 54 will pass through the heating unit 53 to the instrument, and if any current comes in on this circuit other than that normally intended, and which is referred to in this specification as a sneak current, it will in time cause the heating unit 53 to flex the electrode 3, closing at least either one or both of the gaps 20 and 21, thereby grounding the circuit and taking the sneak current away from the instrument being protected by the arrester. I

In Figure '18, a somewhat similar arrangement is provided except that the electrode 3 has two branches, one of which, $5, is a plain metallic contact member engaging the bi-metallic electrode 3 intermediate its ends, the fixed end of whiclr is fastened to an insulator es. However,

in this case, that is, in Figure 18, the incoming circuit wire is connected to a lead wire 66, while the lead wire 5 is connected to the instrument, so

that in the operation of the device sneak cur-- rent coming in fromthe line at 6 5, through the heating unit 63, through the contact at and terminal 65, and the lead. wire 5, sumcient heat is generated to flex the electrode 3 to close the gap circuit at and also open the contact El. This will ground the electrode 3 to the electrode 2 and the flow of the sneak current through the unit 63 will hold this ground circuit closed and the instrument circuit open.

In both Figures 1'7 and 18, an over-voltage will jump the gaps and cause the bi-metallic elements to function as has been previously described. Thus the forms of arrester shown .in Figures 17 and 18 act as a combination of voltage and current arresters;

In Figure 19, the arrester shown is the same as in Figure 13, except the electrodes i l and 15 are plain metallic electrodes having, however, stops 8 and 9 and carbon contacts 6 and i which are shown as being held to their respective electrodes by ears 16 formed from their respective electrodes and having indentations Tl adapted to engage depressions in the carbon contacts 6 and i.

In Figure 20, the bi-metallic electrodes 2 and 3 are similar to those shown in Figure 17, but the auxiliary electrode 86 may be carried over to the position shown, and arranged to engage the auxiliary electrode 34 which carries the sneak current coil 63. In this arrangement, the incoming line wire is connected to the lead-in wire 86, while the lead wire 5 is connected to ground. On passage of snea current through to the instrument throughthe lead wire 4, a contact 78 will be closed between the bi-metallic electrode 3t and the auxiliary electrode 88, thereby grounding the circuit. In this arrangement, it is seen that the sneak current does not enter the gas-filled tube but is shunted around it.

In Figure 21, the heating coil 63 may be eliminated and the thermo-electrode 2 so constructed that it will act in a somewhat similar capacity; that is to say, the incoming line wire is connected to the lead-in wire 64, while the lead-in wire 5 o is connected to ground, and the lead-in wire 66 is connected to a flexible wire 19, the opposite end of which is connected to the free end of the electrode 2. Preferably the wire IQ is of good conducting material such as copper. In this arrangement any sneak current coming in over the lead wire 6% and the flexible wire 19 to the instru-- ment via lead 5, will heat the electrode 2, causing it to flex and contact with the ground electrode 3, thereby shunting the sneak current away from the instrument.

By having an arc gap positioned intermediate the ends of the electrodes, or nearer the fulcrum or the point about which the electrodes move, the heat generated by the current jumping this gap will more rapidly heat up the electrodes and cause them to flex and close the gap contacts,

the electrode. By getting this quick action or movement of the electrodes, the tendency for the than where the gap contact is at the ektremity of arc to melt the metal of the electrodes is thereby greatly reduced. -.'1his arrangement also provides that if the voltage causes the current to jump at the closer gap, for example thegap 20 in Figure 9, the movement of the electrodes toward each other will start closing the gap 2| and the high voltage current will then flnd another path between the electrodes, thereby preventing all the current from passing between the electrodesat one point and consequently reducing the tendency to melt or destroy the electrodes. Thus the effect of the multiple gap arrangement between the electrodes is to quench the are more rapidly and to dissipate the destructive efiect of the arc.

While I have shown in various figures the sealed tube as aseparate unit, it is to be understood that in each case the tube may be enclosed in a housing similar to that shown in either Figures 19 or 12, or any other desiredform.

From what has been said, it will be observed that the details for carrying my-invention into practice may be varied over a considerable range, and I therefore do not wish to be unduly limited in the interpretation of the appended claims.

What I claim is:

1; 'A protective device of the class described including, a sealed tube filled with an inert gas such as neon, a pair of bi-metallic electrodes mounted in spaced relation within the tube, each of said electrodes having a plurality of definite predetermined portions forming arc gaps for the passage of current therebetween.

2. Aprotective device as set forth in claim 1, further characterized in that one set of said predetermined portions is normally closer together than any other set of said portions.

' 3. A protective device of the class described in-, cluding, a sealed tube, at least onebi-metallic electrode having an arc gap surface to engage another are gap surface within said tube, and positive means including an outwardly bent end of said electrode which normally engages the inner wall of said tube for positioning the free ends of said electrode within the tube so as to prevent said are gap surfaces from normally taking a position other than a given predetermined distance said bi-metallic electrode having another are gap surface intermediate its ends and a further arc gap surface within said tube to cooperate with said intermediate electrode surface.

4. A protective device of the class described including, a sealed tube containing an inert gas, and quick arc extinguishing means within said tube comprising bi-metallic electrodes having an initial arc gap for carrying the arc current, and positive means including integral parts of said electrodes and the wall of said tube for preventing said initial arc gap from normally taking a position other than a predetermined distance and means for accelerating the speed of movement of said bi-metallic electrodes to close said are gap as soon as possible after the discharge of current across the electrodes.

. 5. A protective device of the class described including, a, sealed tube containing an inert gas. quick arc-extinguishing means within the tube comprising bi-metallic electrodes having at least -a defined air gap intermediate their ends as well as'a positively fixed initial gap at their free ends,

\ which gap is greater than the intermediately positioned gap for the purpose described.

6. A protective device of the class described ingreases eluding, a sealed inert gas tube. are gap parts spaced in cooperative position within the tube. at least one of said are Bap parts being a bi-metallic thermostatic element, means for preventing said are gap parts from normally taking a position other than a predetermined distance, and. auxiliary bi-metallic members so positioned externally oi the sealed tube and electrically connected to said are gap parts to automatically shunt at least the greater part of said are gap parts on passage of suflicient heat from the tube to said parts.

7. A lightning arrester comprising a container and electrodes normally separated by a gap, at least one of said electrodes being bi-metailic, the electrodes being relatively movable toward each other in response to the passage of current through the gap, and thermally responsive means carried by said container for automatically increasing the current-carrying capacity of the arrester by shunting current around said electrodes.

8. A protective device of the class described including a sealed tube filled with an inert gas, such as neon, a pairoi bi-metallic electrodes mounted in spaced relation within the tube forming at least one are gap. the electrodes being movable toward each other in response to the passage of current through the gap, and thermally responsive means carried by said container for automatically increasing the current-carrying capacity of the protective device by shunting cur-.

rent around said electrodes.

9. A lightning arrester comprising a container and electrodes normally separated by a gap, the electrodes being relatively movable toward each other in response to the p of current through the gap, and thermally responsive means carried by said container !or automatically increasing the current-carrying capacity of the arrester and speeding up the time of quenching the 40 are by shunting current around said electrodes.

10. A protective device or the class described including a sealed tube filled with an inert gas, such as neon, a pair or bi-metallic electrodes mounted in spaced relation within the tube forming at least one arc gap, the electrodes being movable toward each other in response to the passage of current through the gap, and thermally responsive means carried by said container for automatically increasing the current-carrying capacity of the protective device, and at the same time speeding up the time oi quenching the are by shunting current around said electrodes.

11. A lightning arrester having at least a pair of spark gap elements, one oi which at least has thermostatic characteristics, and also having a free end with a contact-engaging-surface thereat, said elements having means intermediate their ends for passing over voltage current therebetween whereby the heat, generated by said current at said means, acts to flex at least the element having the thermostatic characteristics to cause the contact at the free end to engage a part of the other gap element.

12. A protective device of the class described including a sealed chamber supporting therein at least a pair 01 spark gap elements, at least one of which has thermostatic characteristics and both having free ends with contact-engaging surfaces thereat and means for accelerating the speed of movement of the thermostatic element, said means comprising primary arc gap contacts on said elements between the end contacts and the support for the elements; said initial gap being smaller than the gap at the free ends 01' said elements to initiate the first discharge whereby heat will be generated nearer the central portions of said elements, thereby speeding up the operation of the thermostatic element and at the same time preventing, by the speeding up action, the burning of the end contact surfaces of said elements.

LION 8.3RACE 

